1. Field of the Invention
This invention relates to a solid-state color image pickup apparatus which uses a solid-state image sensor such as a charge coupled device (CCD) as an imager for producing an image of an object, and more particularly, to an apparatus which adjusts registration errors or superposition errors of an image for each color produced in the optical image pickup system by using electrical signal processing.
2. Description of the Prior Art
In a color image pickup equipment, color images can be reproduced by producing an image of an object after decomposing it into optical images comprising three-primary-color images of red, green and blue and by superposing these images which have the respective colors. In this connection, since superposition errors, such as registration errors of the images of each color appear on a reproduced color image as a color discrepancy, such errors must be maintained at a minimum level.
Generally in color image pickup equipment, registration errors of the images of each color occur due to a color magnification aberration of the optical image pickup system. These registration errors should be adjusted. Particularly, in case there are no errors in the center part of a picture, the registration errors caused by color magnification aberration tend to increase as the distance from the center part of the picture increases. Therefore, it is not possible to eliminate said registration errors of the optical image pick up system simply by making the registration errors of the center part of the picture zero by using mechanical registration adjustments.
A known color television camera with an image pickup tube is used to execute registration adjustment for eliminating said registration errors by adjusting the mechanical positions of an image pickup plane of the images for each color and by electrically adjusting the deflection system. Also in a solid-state color television camera using a solid-state image sensor comprising, for example, a CCD, the image pickup region could not be adjusted by the deflection system which is unlike the image pickup tube type camera, so mechanical registration adjustment with high precision has been attempted.
In case real time registration adjustment is executed by electrically processing signals in solid-state color image pickup devices, complicated superposition is required since there are few data especially in the vertical direction. Also, the above-mentioned interpolation procedure lowers the resolution, which gives rise to another problem.